Carriages for hoists are also referred to as crane trolleys or as trolley traveling winches. Different embodiments of these have been known. Underflange carriages frequently have two lateral shields which, respectively, support two running wheels, wherein the lateral shields are connected to each other by bolts. It is also possible to mount the load, e.g., in the form of a chain block hoist, to the bolt. Such a carriage is known, for example, from publication DE 10 2004 009 062 A1.
The corresponding running rails exist in different flange widths. Therefore, it is desirable on the part of the manufacturer of hoists to be able to adapt the carriages to different running rails, i.e., different flange widths.
To accomplish this, the cited publication DE 10 2004 009 062 A1 comprises a spacing option between the two lateral shields. To do so, the two lateral shields are connected to each other by means of a bolt-shaped crossbeam, in which case the lateral shields are adjustably supported on said crossbeam. Securing elements in the form of adjustment rings are provided, whereby these can be axially fixed on the crossbeam bolt in order to avoid any unintentional shifting of the lateral shields.
Publication WO 2009/156587 A1 also discloses a carriage with two lateral shields, wherein their relative distance from each other can be adjusted. The lateral shields engage with hook-type extensions in a suspension groove that is provided in the housing of the lifting gear. A threaded adjustment bar 9 is provided for adjusting the distance of the two lateral shields, said threaded adjustment bar connecting the two lateral shields. A rotation of this threaded adjustment bar adjusts the distance between the lateral shields.
Publication EP 0 912 383 B1 also discloses a trolley traveling winch with adjustable track width. Threaded rods connect the two lateral jaws with one another and allow the adjustment of the track width. To so, the threaded rods extend through appropriate openings on the lateral jaws, at which openings said rods are then secured by nuts that are tensioned against one another.
Publication GB 2 128 566 A discloses a carriage with adjustable track width. Again, a threaded spindle is provided for adjustment, said spindle being rotatably supported on a lateral shield yet axially rigidly supported and extending into a threaded bore of the opposing lateral shield. The track width can be adjusted by rotation of the spindle. A load is suspended centered from both lateral shields via pivotable brackets. Referring to this design, the suspended load is automatically centered. However, this requires a relatively high space for construction that results in lifting height losses in the case of hoists and is undesirable.
It has been found that, referring to lifting device, it is of importance that the pulling means extending from the hoist downward for lifting loads be located within relatively narrow limits in the center plane of the running rail. This must be taken into consideration in all adaptations of the track width of a trolley. Consequently, the track adjustment requires that appropriate care be exercised by personnel entrusted with this.
Publication U.S. Pat. No. 1,151,226 discloses a carriage that moves at the bottom of an I-profile bearing rail. The carriage comprises two side parts that rotatably support running wheels, said wheels running on the lower flange of the bearing rail. The two side parts are connected by a threaded bolt that, for distance adjustment, is screwed, with the right-hand thread, into one of the side parts and, with the left-hand thread, into the other of the side parts. Between the side parts, a section of the bolt is exposed. There, it is provided with an annular groove from which a load-bearing bracket can be suspended. By rotating the bolt, it is possible to adjust the distance of the side parts from one another within limits, in which case the load-bearing bracket always remains centered. However, the bolt is subject to bending stress.